The present invention relates to an arrangement for mounting a tubular member made of elastomeric material onto a shaft member. The tubular member may include, not exclusively, dynamic dampers which are, for instance, mounted on a vehicle drive shaft to eliminate any undesired rotational resonant condition of the drive shaft and rubber boots for protecting shaft couplings and other assemblies from moisture and dust.
In motor vehicles, a dynamic damper is sometimes mounted on a drive shaft with the aim of reducing vibrations and noises during use, and may consist of an annular mass, and an elastomeric member in which the mass is insert molded to mount the annular mass on the drive shaft. For the purpose of protecting a shaft coupling of a drive shaft from moisture and dust, a bellows-type tubular boot is often used. Typically, these elastomeric members are attached to the drive shaft by fastening a steel band around the elastomeric member to secure it onto the outer surface of the drive shaft, and are prevented from both circumferential and axial movement relative to the drive shaft. Typically, a crimping arrangement or a threading arrangement is provided in the steel band to join the two ends the steel band. Sometimes, the outer surface of the drive shaft must be suitably machined so as to positively prevent any relative movement between the elastomeric tubular member and the drive shaft.
However, according to such conventional arrangements, because of the need for the work step of fastening the steel band, the assembly work process tends to be more complex than desired. The need for the steel band adds to the effort required to stock and maintain the component parts for both the assembly work and servicing. Also, the shaft rotates at a high speed, and any lack of rotational balance in the steel band could cause an increase in the noises and the vibrations which the drive shaft may produce.
In view of such problems of the prior art, a primary object of the present invention is to provide an arrangement for mounting an elastomeric tubular member onto a shaft which is simple and easy to assemble, and low in cost.
A second object of the present invention is to provide an arrangement for mounting an elastomeric tubular member onto a shaft which is reliable in use, and is relatively free of any rotational imbalance.
According to a preferred embodiment of the present invention, these and other objects can be accomplished by providing an arrangement for mounting a tubular member made of elastomeric material onto a shaft member, comprising: a tubular sleeve member made of resiliently deformable elastomeric material and having an inner circumferential surface adapted to be fitted onto the shaft member; an annular projection formed integrally on the inner circumferential surface of the tubular sleeve member; and an endless band made of relatively rigid material which is disposed on the tubular sleeve member and coaxially surrounds the annular projection; an inner diameter of the annular projection being slightly smaller than an outer diameter of the shaft member, and an inner diameter of the endless band being slightly larger than the outer diameter of the shaft member.
Thus, an elastomeric tubular member can be fitted onto a shaft easily and economically. Because the endless band can be made of a seamless solid ring or a welded ring, it is more reliable in use than conventional steel band fasteners. Furthermore, since the endless band is uniform over its entire circumferential length, it is free from any rotational imbalance. Also, elimination of projecting parts which was inevitable in the conventional arrangement using steel band fasteners is beneficial as it reduces the chance of inadvertently catching or damaging any external object. The endless band may be either fitted onto the tubular sleeve member or insert molded in the tubular sleeve member. According to a preferred embodiment of the present invention, the annular projection is formed in an axial extension of the tubular sleeve member, and the endless band is adapted to be fitted onto or insert molded in the axial extension.
To facilitate the mounting of the sleeve member, the inner diameter of the tubular sleeve member may be substantially equal to the outer diameter of the shaft member, and/or at least one of axial ends of the annular projection may be provided with a tapered section. When the annular projection is formed in an axial extension of the tubular sleeve member, and the endless band is adapted to be fitted onto or insert molded in the axial extension, the axial extension of the tubular sleeve member may be provided with at least one axial slit to aid placement of the endless band onto the axial extension. Even when any sealing function is required, the annular projection which is necessarily tightly fitted around the shaft member ensures a favorable sealing capability. This arrangement is suited for application to dynamic dampers, and, in this case, the tubular sleeve member may be connected to an annular mass member which coaxially surrounds the sleeve member, via a radial rib made of resilient elastomeric material. Thus, the dynamic damper can be made by simply insert molding an endless band in a single-piece member made of suitable rubber-like elastomeric material.
According to another preferred embodiment of the present invention, the tubular sleeve member including the axial extension is provided with an inner circumferential surface having a uniform inner diameter, and the annular projection is formed by fitting the endless band having a slightly smaller inner diameter than an outer diameter of the axial extension onto the axial extension. This simplifies the molding of the tubular sleeve member, and may even allow use of a conventional tubular sleeve which was originally adapted for a steel band fastener. In this case also, the axial extension of the tubular sleeve member may be provided with at least one axial slit to aid placement of the endless band onto the axial extension.
Another important application of the present invention may be found in securing an axial end portion of a dust boot made of elastomeric material onto a shaft member.